Conventionally, in a vehicle door opening and closing device, there is known a configuration in which an actuator (a support member) that opens and closes a tailgate by expansion and contraction drive in an axial direction is provided between a periphery of an opening portion on a vehicle body side and the tailgate (a back door) provided in an openable and closable manner at the opening portion (see, for example, Patent Literature 1).
Such actuator includes a tubular first housing, a second housing which has a diameter larger than that of the first housing and into which the first housing is inserted, a motor provided in the first housing, a drive shaft (a screw spindle) which is connected to a rotation shaft of the motor via a reduction gear and is disposed coaxially with the rotation shaft, a spindle nut which is fixed to the second housing and is screwed to the drive shaft, a compression coil spring which is accommodated in the second housing and urges the first housing and the second housing in the expansion direction.
The motor and the reduction gear are provided in the first housing. Also, a bearing holder is provided at an end portion of the first housing on the second housing side. The bearing holder holds a bearing (a ball bearing), and rotatably supports an end portion of the drive shaft on the reduction gear side via the bearing. As a result, one end of the rotation shaft of the motor, the reduction gear, and one end of the drive shaft are supported by one bearing, thereby achieving miniaturization of the actuator.